Review on Accurately Sight In Your Shotgun With The Sightmark Red Laser Boresight by David Schweigert

I bought this laser bore sight to practice my shotgun mount and swing. It works very well for this. Obviously, because of distance and ambient lighting effects, it works best indoors, but an external wall or other suitable outdoor surface may also work well if not in bright sunlight. The only limitation of this product was the "reliability" of the on-off function of the laser.As others have said, there is no on-off switch; rather, the light is energized by placing all three watch batteries in the unit and screwing the end piece on. Getting the laser to work usually takes some playing with the tightness of the threaded end cap. Also, there are times when the laser is on, but turns off when placed in the shotgun and closed (I have an O/U - I didn't try it in a semi-auto or pump). These are fairly minor annoyances, taking little time to overcome, but really caused others to severely downgrade their ratings.One other caution: the light can be energized by simply leaving all three batteries in the unit even without the end cap attached, so I store it with only one battery inside and two loose in the handy pouch.